Solvent refining of hydrocarbon oils



Patented Nov. 2.), 1938 UNITED STATES 2,138,772 SOLVENT nnrmmg grnrnaoonnnon Erich Saegebarth, Long Island City, N. Y., is-

signor to Edeleanu Gesellschaft, m. b. H., a corporation of Germany NoDrawing. Application October 9, 1933, Serial No. 692,906

8' Claims.

extraction of undesirable constituents with selective solvents.

The invention has particular reference to the production of improvedlubricating oils from heavy petroleum distillates, cylinder stocks, andresidues, which contain substantial amounts of undesirable asphaltic,resinous, and color-bearing compounds, such as those from Mid-Continentfields. Imention these diflicultly refinable oils because of thestriking improvement which can be effected by refining them according tomy invention, but it will be understood that my invention findsadvantageous application to the refining of hydrocarbon oils generally.

The aimof modern processes for refining mineral oil is to remove theundesirable constituents from crude oils or fractions thereof byextraction with selectiy'e solvents which do not react with the oil. Thesolvents employed separate the desirable constituents from theundesirable constituents to a greater or less degree, depending upon thenature of the solvent used and the conditions of use. Such solvents arerelatively immiscible in the desirable hydrocarbons, so that an excesscan be employed which will separate out, after mixing and standing, intoa separate layer or phase which will contain the undesirableconstituents extracted by the solvent.

This latter layer or phase, comprised of the bulk of the solvent andcontaining the extracted materials, is commonly known as the extractlayer, extract solution or extract phase. The layer or phase comprisedof the refined oil, together with that portion of the solvent dissolvedtherein, is commonly known as the raflinate layer, rafiinatesolution orrafiinate phase. The non-solvent portions of these layers, which areobtained by separately drawing ofi the two layers and removing thesolvent contained therein, are known as the extract and rafiinate, thelatter constituting the refined product.

I have discovered that para-chlorophenol has very good selective solventproperties rendering it highly advantageous for use in refining mineraloils. Para-chlorophenol dissolves to a great extent the asphaltic andcolor-bearing compounds which may be present and hence permits of animproved refining of heavy stocks containing such materials, as comparedwith the results obtained from using such solvents as liquid-S02 whichhave a low solvent power for asphaltic and colorbearing compounds. Inaddition, this solvent readily dissolves unsaturated hydrocarbonsgenerally and also has a good solvent power for oxidizable andsludge-forming materials, all of which areundesirable in lubricatingoils for use in internal combustion engines.

Particularly striking results are obtained in the refining ofMid-Continent and naphthenic base residual oils for lubricatingpurposes, as these oils cannot be successfully refined with-suchsolvents as liquid-S02 and are considered very difiicult to refine. Therefined oils obtained by the practice of my invention have a very lightcolor and are greatly improved in their physical and chemicalproperties, including gravity, viscosity index, viscosity-gravityconstant, carbon residue, and stability against sludging and oxidation.

As para-chlorophenol readily dissolves unsaturated and aromatichydrocarbons it may be employed to advantage for refining all types andfractions of mineral oils from which it is desired to remove suchcompounds, and it has general application in the field of solventrefining of hydrocarbon oils.

Extraction'can be accomplished in the same manner as with selectivesolvents heretofore employed. The oil may be extracted one or more timeswith the solvent in batches; or may be extracted by being passedcounter-currently to the solvent through a vertical tower or through aseries of mixing devices and settling tanks. Owing to the density of thesolvent which I employ the extract layer will in each case be the lowerlayer.

The portions of solvent contained in the raffinate. and extractsolutions can be removed and recovered therefrom by distillation,preferably under vacuum. The necessary heating will not decompose thesolvent which I employ and this permits of repeated use with littlemake-up required. This is of importance from the economic and operatingstandpoint.

The following examples illustrate modes of carrying out my invention anddemonstrate the remarkable results which can be obtained.

Example 1 In the first example an untreated Mid-Continent residual stockwas extracted by the multiple-batch method. The stock was firstextracted with 200% by volume of para-chlorophenol, at a temperature of113 F., and the resulting raffinate layer was divided out and extractedwith 100% by volume (relative to the original volume of untreated stock)of fresh solvent at the same temperature. The resulting second rafiinatesolution was freed of solvent to secure the final rafflnate.

The action of the solvent which I employ may be greatly improved bycarrying out the extraction of the oil therewith in the presence ofpropane or other low-boiling saturated hydrocarbon. As additionalexamples, I mention the low-boiling paramns: ethane, butane, pentane,etc. Mixtures of these may likewise be used. A low-boiling fraction ofsaturatednaphtha may also be S02 extraction of naphtha. 'Ihe presence ofthese saturated hydrocarbons increases the selectivity of the extractionand otherwise improves the extraction, thus permitting of greaterraffinate yields and/or higher quality ramnates. Since they arelow-boiling they may be easily removed from the ramnate by distillation.

Example 2 In this example the same untreated Mid-=Continent residualstock that was used in the pre= ceding example was employed. The stockwas dissolved in 300% by volume of propane and the resulting solutionwas extracted successively with two batches of 100% by volume ofpara-chlorophenol, at a. temperature of 86 F.

The following'table gives the characteristics of the raifmates obtainedin these two examples as compared with the characteristics of theoriginal stock. In the table the gravity is given in degrees A. P. 1.,the viscosity in seconds according to the Saybolt Universal method ormeasurement, "V. I. stands for the viscosity index, "V. G. C. stands forthe viscosity-gravity constant, and carbon stands for the carbon residuedeter- Dissolved in 800 Egitfiacted vol. percegt pro- W1 parapane anexggii chlorophenol traoted with 200+100 para-chlorost 113 F. phenol 2l00% at 86 F.

20. 0 26. O 26. 4 997 502 361 147 104 83 79 103 96 0. 859 0. 819 0. 8205. 6 2. l 0. Color Black Green Green Raflinate yield, per

cent by weight 48 Examples 3 and 4 For the purpose of illustrating therelative solvent power and selectivity of para-chlorphenol andortho-chlorophenol for refining lubricating stocks heretofore consideredvery diflicult to treat successfully, a heavy distillate from aMid-Continent crude oil, which had been dewaxed but otherwise untreatedbefore solvent extraction, was subjected to extraction by the'multiplebatch method using these solvents in quantities of 150% to 200% byvolume relative to the original volume of the untreated stock, and attemperatures from 35 to 1200 F.

The results of these tests are given in the following table:

sect rar g fia or- 0 ortho-chloro phenol at phenol 120 F. 35 F 23. 229.1 27. 4 1287 643 761 92 73. 2 77. 4 78 103. 5 97. 5 0 2O 16 Garb.res.-- 1.9 0 28 0. 60 NPA color (diluted) Darker than 8 3% 4% Yieldvolume percent. 60. 4 51. 7

From the foregoing results it appears that the yield depends upon thenature and amount of solvent used as well as upon the temperature. Itwas found necessary to use a comparatively low temperature for treatingwith ortho-chlorocassava phenol because the solubility of the oilincreases so much that at. about 45 F. no separation could be efiected.

Examples 5, 6 and 7 The relative effectiveness of para-chlorophenol andphenol is evident from the following results of treating the sameMid-Continent dewaxed distillate that was used in Examples 3 and 4, with125% and 100% by volume of para-chlorophenol at F. as compared with 200%by volume of phenol at F.

These results indicate that para-chlorophenol is about twice asefiective as phenol as a solvent for extracting undesirable constituentsof lubricating oil produced from Mid-Continent stock, 100% of the formerapplied in two treatments producing substantially the same yield andquality of rafinate as 200% of the latter applied in three treatments ata slightly higher temperature. I have also found, as shown by theresults of Example 3 compared with those of Example 7, thatpara-chlorophenol is much more selective than phenol when used in thesame amount under the same treating conditions, the ramnate producedbeing of a much superior quality.

I claim the following as my invention:

1. In the refining of heavy residual lubricating oil, such as derivedfrom mixed-base crude petroleum with monochlorphenol in the absence ofan auxiliary selective solvent, the method comprising extracting theresiduum containing darkcolored material, residual carbon-formingconstituents, as well as constituents of low and high viscosity index,with chlorphenol consisting essentially of the para. form of thecompound substantially free from the ortho compound, forming an extractphase comprising low viscosity index constituents, residualcarbon-forming constituents and dark-colored material dissolved in thesolvent, and a rafiinate phase comprising high viscosity index oilhaving a relatively low residual carbon content and substantially freefrom dark-colored material.

2. The method of claim 1 in which the extraction is performed in thepresence of a low boiling diluent of the class of the low boilingpararlins and saturated naphthas.

3. The method of claim 1 in which a low boiling diluent of the characterand action of propane is added to the oil prior to separation of theextract and ramnate phases.

4. A process of refining mineral oil containing both high viscosityindex hydrocarbons and low viscosity index hydrocarbons, comprisingextracting the oil with a solvent consisting essentially ofpara-monochlorophe'nol to form a raifinate layer containing the highviscosity index hydrocarbons, and an extract layer containing the lowviscosity index hydrocarbons of said mineral oil dissolved in thesolvent, separating said layers from each other, and recovering thesolvent therefrom.

5. The method of claim 4 in which the extraction is performed in thepresence of a low boiling diluent of the class of the low boilingparafilns and saturated naphthas.

6. The method of claim 4 in which a low boiling diluent of the characterand action of propane is added tothe oil prior to separation of theextract and raffinate phases.

7. In the refining of heavy residual lubricating oil, such as derivedfrom mixed-base crude petroleum with monochlorophenol in the absence ofan auxiliary selective solvent, the-method comprising extracting theresiduum containing darkcolored material, residual carbon-formingconstituents, as well as constituents of low and high viscosity index,with chlorophenol consisting essentially of the para form of thecompound substantially free from the ortho compound, forming an extractphase comprising the low viscosity index constituents, residualcarbon-forming constituents and dark-colored material dissolved in. thesolvent, and a railinate phase of high viscosity index oil comprisingaround 50% of the residuum having a Conradson carbon content of theorder of 1.8% and substantially free from dark-colored material.

8. In the refining of heavy residual lubricating oil, such as derivedfrom mixed-base crude petroleum with monochlorophenol in the absence ofan auxiliary selective solvent, the method comprising diluting theresiduum containing darkcolored material, residual carbon-formingconstituents, as well as constituents of low and high viscosity index byaddition thereto of a low-boiling petroleum hydrocarbon, extracting thedilute mixture with chlorophenol consisting essentially of the para formof the compound substantially free from the ortho compound, forming anextract phase comprising low viscosity index constituents, residualcarbon-forming constituents and dark-colored material dissolved inthesolvent, and a rafllnate phase comprising high viscosity index oilhaving a relatively low residual carbon content and substantially freefrom darkcolored material.

ERICH SAEGEBARTH.

Cil

